(1) Field of the Invention
The present invention relates to a method of manufacturing ceramic bodies having a construction such that cells are alternately sealed at one but not both end surfaces of a ceramic honeycomb structural body.
(2) Prior Art Statement
Generally, various methods of manufacturing the ceramic bodies having the construction such that the cells are alternately sealed at one but not both end surfaces of the ceramic honeycomb structural body have been known. FIGS. 5a-5c are schematic views respectively explaining one embodiment of the known method of manufacturing the ceramic bodies. According to FIGS. 5a-5c, the known method of manufacturing the ceramic bodies will be explained. At first, as shown in FIG. 5a, a rubber mask 54 having holes 53 pierced at portions corresponding to cells 52 to be sealed is prepared, and then the mask 54 is set manually to an end surface of a ceramic honeycomb formed body 51 (ceramic honeycomb structural body before sintering).
Then, as shown in FIG. 5b, the end surface of the ceramic honeycomb formed body 51, to which the mask 54 is arranged, is immersed into a sealing slurry 55 by applying a pressure to the ceramic honeycomb formed body 51 from the upside. Thereby, the slurry 55 is filled into the cells 52 through the holes 53 of the mask 54. The same process is performed with respect to the other end surface of the ceramic honeycomb formed body 51 so as to fill the slurry 55 into the cells 52. In this case, in order to obtain a construction such that the cells 52 are alternately sealed at one but not both of the end surfaces, use is made of the another mask 54 having holes 53 pierced oppositely with respect to the holes 53 of the mask 54 used for the one end surface mentioned above. Then, as shown in FIG. 5c by a cross section, it is possible to obtain the ceramic honeycomb formed body 51 having the construction such that the cells 52 are alternately sealed at one but not both of the end surfaces of the ceramic honeycomb formed body 51. Finally, the thus obtained ceramic honeycomb formed body 51 is sintered so as to obtain a target ceramic body.
However, in the known method of manufacturing the ceramic body mentioned above, there are drawbacks such that it is difficult to make the mask 54 having the holes 53 at predetermined positions and to set precisely the mask 54 to the end surface of the ceramic honeycomb formed body 51. Particularly, in a large size ceramic body required recently having a diameter of 300 mm for example, the number of the cells 52 becomes several ten thousands, and thus the drawbacks mentioned above become further difficult. Moreover, since the mask 54 is set manually to the end surface of the ceramic honeycomb formed body 51, workers need experience for such a process, time is necessary for this process, and it is not possible to perform automatic processing. Further, it is necessary to clean up the mask 54 after end of work so as to reuse the mask 54, but, since the mask 54 has enormous cells 52, there is a drawback such that it is very troublesome to clean up the mask 54.
An object of the present invention is to eliminate the drawbacks mentioned above and to provide a method of manufacturing ceramic bodies wherein the cells can be easily sealed at the end surface and it is easy to achieve an automation process.
According to the invention, a method of manufacturing ceramic bodies having a construction such that cells are alternately sealed at one but not both end surfaces of a ceramic honeycomb structural body by filling a sealing slurry into predetermined cells at both end surfaces of a ceramic honeycomb formed body and sintering the ceramic honeycomb formed body, comprises the steps of: forming a mask for respective ceramic honeycomb formed bodies by arranging a sheet on an end surface of the ceramic honeycomb formed body and piercing holes in the sheet at positions corresponding to the predetermined cells; immersing an end portion of the ceramic honeycomb formed body to which the mask is arranged into the sealing slurry; and filling the sealing slurry into the cells through the holes pierced in the mask.
In the present invention, since use is made of the disposable sheet to which the predetermined holes are pierced every sealing processes instead of the mask, it is possible to reduce a mask making process and a mask setting process for the end surface of the ceramic honeycomb formed body. Moreover, it is possible to perform a cell position detecting process by means of an image processing and also it is possible to perform a hole piercing process in the sheet by means of a laser processing. Therefore, it is possible to realize an automation.
As a preferred embodiment, the piercing step to the sheet arranged at the end surface of the ceramic honeycomb formed body is performed respectively for sub-blocks obtained by dividing the cells at the end surface into sub regions. With respect to the end surface of the large size ceramic honeycomb formed body having for example a diameter of 300 mm, if the hole piercing process for all the cells is performed with reference to one standard cell pitch obtained for particular few cells, the cell pitch is deformed due to changes of drying states, material lots and forming conditions. In this case, an error over one cell with respect to a normal hole piercing position occurs. Moreover, in the case that the hole piercing process is performed by detecting all the positions of the cells at once and by piercing all the holes every time its position is corrected by calculating a distance from a center, it takes a lot of time for a data transmission and a position correcting calculation for all the cells if use is made of an image processing technique, a laser processing technique and a computer for data processing. If the hole piercing process is performed for every sub-block, deformations of the cell shape and the cell pitch are small in the sub-block region. Therefore, an error is within one cell even if the hole piercing process is performed with reference to one standard cell pitch obtained for particular few cells. Moreover, since the number of the position correcting calculations can be reduced, it is possible to reduce a time required for the position correcting calculations. Further, as a preferred embodiment, a diameter of the hole pierced in the sheet is set in such a manner that the hole has an area of 30-70% of an area of respective cells. In this embodiment, if a slight cell pitch variation occurs in the sub-blocks, it is free from care that the hole is made to a cell wall or adjacent cells since a diameter of the hole is small with respect to the cell.